Kingdom Protoctista Hogg, 1860 Phylum Bacillariophyta Engl. & Gilg (1919) - diatoms see [unranked] Diatomea Kütz. (1844) Class Coscinodiscophyceae Round & R.M. Crawford (1990) - radial centrics Subclass Thalassiosirophycidae Round & R.M. Crawford (1990) see Class Mediophyceae Medlin & Kaczmarska (2004) Order Thalassiosirales Glezer & I.V. Makarova (1986) Family Cyclotellaceae see Family Stephanodiscaceae Glezer & Makarova (1986) Genus Cyclotella (Kütz.) Bréb. (1838)